In many classes such as Mini 650s, Class40s and Imoca60 it is mandatory to paint your boat number on the deck, in Cat Zero events you also have to paint an area of 4sqm in high visibility colour.

I've seen work done so badly on new boats that it made me cry. Painting numbers is not easy and doing it well even less. The most complicated case is when your non slip is of diamond shapes in the mold of the deck as seen on many production boats rather than a non slip paint finish. This is because any when trying to mask the masking tape will not create a good seal with the diamond shapes of the gelcoat deck. We cant sand down the diamond shapes to get to a smooth surface, so ideally we want to preserve the non slip properties of the deck but still be able to paint over it.

If you have to apply anti-slip to the whole boat, it is no small job. When talking of standard non slip paint, rather than a gelcoat diamond grip, if the old paint is just faded or worn out, you may want to apply a coat over the old one. But, if it peels you will be forced to sand everything down. This is if you want to apply the anti-slip on smooth deck get a good result.

Perfect numbers even on a difficult surface such as gelcoat with 'diamonds' molded antiskid - photo © Global Solo Challenge

If you need to paint the numbers on a new boat or refresh them, you must first sand down and return to gelcoat, in case of a diamond finish you need to clear off the peeling parts with a wire brush or carefully with a blade to preserve the diamond shaped gelcoat. Painting new numbers over old ones will probably be a bad job. Also because colours like red don't have a great coverage capacity and you have to work on a white background. If the background is uneven after sanding, apply a primer or a white undercoat. Then you will have to paint the number the same way you can use to apply anti-slip on deck.

Apply the anti-slip on deck: masking

Before starting, you have to tackle one of the longest and most boring jobs, masking everything you don't want to paint. You will need some blue or green masking tape, capable of stretching to follow curves. You will also need a cutter blade for the places where it will be easier to tape and cut off the excess.

Going back to the numbers, trying to write them by hand with masking tape will result in a bad job. Go to any graphic design shop and for a small sum they will print the numbers or rather the negative frame. Have them print it on the same adhesive material you use for masking. When placing the number on the deck, everything is easy if you stick the mask on a smooth surface. If, on the other hand, you have sanded the number but you have still anti-slip at the edges of the sanded area the work is more complicated.

Use butyl sealant for difficult spots - photo © Global Solo Challenge

The mask will not adhere well to anti-slip painted surfaces and when you paint the number the paint will find its way under the mask. But here's a secret on how to apply anti-slip and mask even the most difficult spots. For these situations you can go to a DIY store and buy some butyl. It is the mastic used to lay kitchen sinks, it does not dry, it does not stick permanently but stops the paint. Once you have placed the number (or the area to be masked) make a very thin butyl salami and press it on the edge of the mask. Once pressed well, follow the outline with a cutter and remove the excess butyl from the side to be painted.

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